Process for sterilization or pasteurization of liquids



A. MULERTZ. PROCESS FOR STERILIZATION OR PASTEUHIZAJIOH 0F LIQUIDS.

APPLICATlON FILED AUG.23. 1911 1,879,875. I Patented May 31,1921

2 SHEETS-SHEET I- A. MULERTZ. PROCESS FOR STERILIZATION ORYPASTEURIZATION OF uqums.

APPLICATION FILED AUG-23, 19l9. 1 ,379,8'75, v Patented May 31, 1921.

2 SHEETSSHEET 2.

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ANDRE M-fi'LERTZ, or ooriaNnAeEN, DENMARK.

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Specification of Letters Patent. Patented May 31;:1921- Application filed August 23, 1919. Serial No. 819,477.

To all whom it may concern Be it known that I, ANDRE MI'iLnn'rz, a subject of the King of Denmark, residing at Copenhagen, in the Kingdom of Denmark, have invented new and useful Improvements in Processes for Sterilization or Pasteurization of Liquids, of which the following is a specification.

Various liquids, for instance milk, are deteriorated by being conveyed, at high speed and high pressure through narrow tubes. This drawback has manifested itself especially by the sterilization or pasteurization of such liquids, when the liquid is conveyed through horizontal tubes bent in zigzag manner, there appearing in these bends partly an excessively great resistance against the flow, and partly drawbacks due to the liquid striking the bends, with a shock. In order to attain an eflicient uniform heating and cooling, the tubes must be narrow, as too wide tubes would have the effect that only the outer layer of the liquid would be efliciently heated or cooled, while the inner layers would only to a very slight extent be exposed to the heating or cooling action.

The above mentioned drawbacks are avoided by the present invention, which relates to a sterilization or pasteurization process for liquids by whichprocess the liquid under pressure, during the heating as well as the cooling process, is conveyed through narrow tubes at a relatively slow speed, so that sterilization or pasteurization may be eifected in thoroughly efficient and satisfactory manner at a temperature of for instance 130 C.

This result is attained by conveying the liquid according to the counter-stream principle during heating as well as during cooling, throu h systems of vertical or inclined narrow tubes at such a rate of speed that the liquid is exposed to the highest and lowest temperature for only the shortest possible time, after having previously been heated gradually, and then again gradually 1 cooled.

An apparatus for carrying out the process in practice is illustrated on the drawing,

Figure 1 shows a vertical section of the apparatus with vertical heatmg and cooling tubes Fig. 2 the same in top view; and

Fig. 3 a vertical section of the apparatus with the heating and cooling tubes dis-V posed obliquely.

1 is the supply tube for the liquid which is pumped into the tube by means of a pump, not shown on the drawing. The tube 1 has, at its upper end, a funnel-shaped extension2, which is fastened to the bottom 3 of a receiver 4 fitted with supply and discharge tubes 5 and 6, respectively, for the heating medium which may, for instance, be steam. The receiver 4 is "covered, on the outside, with an insulating material 7 inclosed in a metal casing 8. The receiver 4 is closed, at top, by a cover 9. In the latter and in the bottom 3, there are holes for narfunnel-shaped extension 11 of a tube 12, whose opposite funnel-shaped end 21 is connected to the cover 13 of a receiver 14. This receiver is fitted with supply and discharge pipes 15 and 16, respectively, for the cooling medium which may, for instance, be cold water. In the cover 13 and in the bottom 17 of the receiver 14, there are holes, for narrow tubes 18 whose lower ends communicate with a funnel-shaped extension 19 on a discharge tube 20 for the sterilized liquid, the said tube being connected to the bottom 17'.

The apparatus acts in the followingmanner:

By means of the pump, the liquid to be sterilized or pasteurized is pressed into the tube 1 and up into the extension 2 thereof, from where it ascends throu h thetubes I0 7 row tubes 10 communicating, at top, with a at a rate of speed correspon ing to the time required by the sterilization of the liquid treated, for instance about one inch per sec the steam flowing into the receiver, to the actual sterilizing or pasteurizing temperature. The liquid passes then, by way of the connecting tube 12, into the cooling vessel 14, it being distributed, in the extension 21, to all the tubes 18 in the receiver 14. The temperature of the .liquid is here radually reduced, the liquid being coole the heated water ascending, along the "outside of the tubes 18 until, before it leaves the lower ends of the tubes 18, the liquid is actuslightly by ated by the cold water entering through the tube 15. By way of the tube 20, the sterilized or pasteurized liquid flows to a closed and disinfected tank, which is not shown on the drawing.

In order to prevent the liquid from being caused by the heat to boil in the apparatus, there is provided, in the discharge tube 20, a counter-pressure valve 22 and the loading of this valve is adjusted in such a manner that it will be able to exert a counter-pressure exceeding the pressure which may be produced in the apparatus by the generation of steam at a certain temperature'when counter-pressure is present.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is 1. lFhe process of sterilizing liquids which consists in passing the liquid continuously in one direction While subjecting it to unianswers formly increasing temperature, and then subjecting it to uniformly decreasing temperature while passing continuously in one direction.

2. The process of sterilizing liquids which consists in subjecting the liquid to a uniformly increasing temperature while slowly passing vertically continuously in one direction at a pressure exceeding the pressure of saturated vapors of the treated liquid at the initial temperature of the heating medium, and then subjecting it to a uniformly decreasing temperature until cooled down to the temperature of the cooling medium while passing continuously in one direction under the same pressure.

In testimony whereof I have signed my name to this specification. r

ANDRE MULERTZ.

Witnesses:

V. BELsoHNEn, E. W. ELLSKEBE. 

